• Journal of Ocean Engineering and Technology
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• v.25 no.1
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• pp.27-31
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• 2011

The previously developed method of estimating the propulsion performance of a UUV was applied to the high speed UUV, which is propelled by commercial thrusters. The thrusters were selected with an overdesign mentality; in other words, their capacities were excessive. At that point, the designer's concern was focused on a question regarding at what rpm the UUV could reach the design speed. Because the developed method required thrust coefficient curve data, the researchers asked for the POW data of the thrusters from the manufacturer. From the data, the researchers extracted the thrust coefficient and estimated the rpm value of design speed for the UUV. Finally, the researchers compared the estimated value and the result from a self-propulsion test using a VPMM (Vertical planar motion mechanism) test at a towing tank in MOERI.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.510-515
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• 1993

본 연구에서는 저속에서도 시스템의 자세 제어가 용이하게 하기 위하여 추진기 뒤에 제어판이 위치하도록 설계하였으며, 일반 서보 시스템과는 달리 무게와 공간 제약이 크고, 제어판 운동에 따른 외란 등록성의 변화가 심하므로 push-pull 형태의 소형, 고출력 편로드 복동 복수 실린더의 작동기를 설계하였다. 또한 일반적으로 서보밸브와 작동기는 일체형으로 설계되나 본 시스템의 공간상 심한 제약으로 인하여 서보밸브와 작동기를 분리하는 방법으로 구조설계를 하고 그 사이 유로는 매니폴드식으로 하여 동력전달을 하였다. 설계된 구동장치를 실제 정밀제작하여 실험을 수행하였으며, 시뮬레이션 결과와 실험에 의하여 얻어진 결과를 비교 분석하여 설계의 타당성 및 시스템의 성능을 검증하였다. 고속 수중운동체에 대하여 저속에서 자세제어를 용이하게 하고, 제한된 좁은 설치공간의 문제점을 해결하기 위하여 1) 추진기 후미에 독립된 4개의 상, 하, 좌, 우 제어판 설치 2) 서보밸브는 몸체에, 작동기는 Tail Tube에 분리 작동 설계 3) 소형의 편로드 복동 복수 실린더로 설계 구성된 유압식 구동장치는 시뮬레이션과 실험 결과를 통하여 시스템의 타당성을 입증하였다. 그러므로, 개발한 구동장치는 저속에서도 큰 제어력으로 자세 제어가 용이하기 때문에 얕은 수심에서 발사시 예상되는 위험 요소를 상다ㅇ 개선 시키므로써 운용범위의 다양화를 가져 올것으로 기대된다.

• Journal of Ocean Engineering and Technology
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• v.32 no.1
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• pp.68-75
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• 2018

This study deals with the heading angle and depth keeping control technique for an ROV with multiple horizontal and vertical thrusters by thrust allocation. The light work class ROV URI-L, which is under development at KRISO, is a redundant actuating system with multiple thrusters that are larger than the ROV's degree of freedom. In the redundant actuating system, there are several solutions for a specific ROV motion to be performed. Therefore, a thrust allocation algorithm that considers the entire propulsion system should be regarded as important. First, this paper describes the propulsion system of the ROV and introduces the thrust allocation method of each motion controller. In addition, the performance of the controller is examined using a heading angle and depth keeping control test in a stationary state.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.129-134
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• 2002

This study is focused on the layout design with sizing for the main propulsion shafting with controllable pitch propeller system. For appropriate design and successful manufacturing of controllable pitch Propeller system, it is based on specifications to be required from the customer as well as the stresses calculation and analysis of main propulsion system for hollow shafting. And it must be performed according to the U.S military specifications MIL-STD-2189(SH) with drawing of NAVSHIPS 803-2145807, and also the stress analysis by applying safety factor. The results are as follows : 1. For the main propulsion system with controllable pitch propeller, it is designed the following items propeller diameter, hub diameter, dimensions of oil distribution or actuating unit based on shaft mounting type, diameters of propeller and intermediate shaft, dimension of split muff coupling, coupling flange thickness and of coupling bolt diameter. 2. As the results, we can get complete our own design ability for the main propulsion shafting with controllable pitch propeller system with critical data which are necessary to establish shafting arrangement from the ship building companies.

• Journal of Power System Engineering
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• v.13 no.5
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• pp.18-24
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• 2009

This paper shows the result of development about the revolution system of azimuth thruster which of power is less than 250kW for small ship. Advanced Azimuth revolution system can revolve propeller and rudder from 360 degree so that this system for vessel maneuvering can be excellent of propulsion effectively. Fluid power control system for azimuth thruster is designed with PID control system by using CEMTool/SIMTool program. And the actuator used for servo valve can control rudder angle, pressure and direction. The first, We had a test for the angle control of revolution system. The result of angle control confirmed that it has the good efficiency from experiment result of time input degree $30^{\circ}$, $90^{\circ}$ and $180^{\circ}$. The second, We had to a test for the pressure characteristic of hydraulic motor. As a result, We confirmed the maximum pressure 3.5MPa and steady state 0.7MPa nom experiment result of time input degree $30^{\circ}$. In this paper, it is identified the pressure characteristic of hydraulic motor and angle control for azimuth thruster by AMESim, and it has been confirmed the usefulness of AMEsim modeling was verified by comparison between AMESim simulation results and experiments results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.955-962
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• 2002

According to the trends of construction of large size vessel with high power, the natural frequencies of the bending modes of propeller blades have been lower than the past. Therefore, it is expected that the noise and vibration problems of the marine propeller are frequently occurred. As main issue of the propeller noise and vibration problem, the cavitation noise and singing noise due to the flow induced excitation of the bending modes of propeller blade in the high frequency range has been studied by the hydrodynamic researchers in the view point of the excitation force reduction. In this paper, the vibration mode characteristics of propeller with a large diameter in very large vessel are investigated by the vibration analysis of the finite element method using MSC/Nastran and the vibration measurement by the impact test on the propeller blade. According to the results, the natural frequencies of various blade bending modes in water entrained condition could be estimated from the natural frequencies taken by the measurement and free vibration analysis in the dry condition, and it could be estimated how the high frequency noise such as singing is generated from the blade bending modes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.76-81
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• 2006

This paper deals with a fuel metering unit (referred to as FMU) for air breathing engine. The proposed FMU consists of a constant pressure drop valve and a metering valve, both of which are controlled by servovalve. Linear analysis derived from a nonlinear mathematical model of FMU is carried out to find major parameters on the system performance. Numerical results using established model of FMU were in good agreement with the experimental results. It is also shown that the system stability is improved by reducing the constant pressure drop at metering valve and applying the triangular orifice to constant-pressure-drop valve through the simulation and experiments.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.33-38
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• 2007

Recent, The propeller had high performance according as high performance of small ship. So, We has the development for azimuth thrusters. This Paper has structure improvement of steering support flange in azimuth thrusters. Steering support flange is very important part. because, Steering support flange supports all weight of azimuth thrusters. We has static & dynamic analysis of Steering support flange, and we discover the very safety. So, We has optimum design for the cost reduction. The first method of optimum design, We has the thickness reduce to 30mm from 5mm. Next method of optimum design, We had added stiffener. And we has the structure & dynamic behavior analysis. We had to dynamic behavior analysis. The first, We had to modal analysis. The result of 1st-modal analysis is that original model had to 76.48hz and new model had to 200.9hz. The second, We had to harmonic analysis. The result, We gave the thrust power to steering support flange. and We had to frequency analysis to $0{\sim}500hz$. The result, Deflection ration reduce to 16.64.

• Special Issue of the Society of Naval Architects of Korea
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• 2011.09a
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• pp.43-46
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• 2011

The noise characteristics of multi-purpose dive support vessel show the different patterns such as types of noise sources, accommodation arrangement and etc due to its operation. Especially, the tunnel and retractable thruster for the dynamic positioning should be considered at the noise analysis. The floating floor is selected as the main measure of noise reduction and is constructed at the deck near the noise sources. In this paper, the noise analysis of dive support vessel is based on the estimation of noise sources and floating floor and SEA (Statistical Energy Analysis) is used for analysis of the air-born noise and structure-borne noise. The noise analysis of air conditioning system is also carried out and the noise results of cabin room are reviewed.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.1
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• pp.73-83
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• 1990

A theorectical method is presented for the calculation of the effective wake in an axisymmetric sheared inflow. The effective wake is essential in the design of optimal propulsor and in the reduction of propulsor induced vibration and noise. The nominal wakes are mathematically modelled and the effective wakes are calculated using the computer program developed on the basis of the linear momentum theory. The results show that shear effects arc dominant near the hub and the effective wakes reveal some differences near the hub for the moderately and heavily loaded propulsors but they arc well coincided with the other experimental or theorectical results for the lightly loaded propulsors. To improve the results it may be necessary to consider nonlinear terms neglected in this study and body boundary condition on hub.